Igniter for coal furnaces



Feb. 6, 1934. A. SHEARMAN 1,945,708

IGNITER'FOR COAL FURNACES Filed Feb. 8, 1933 Patented Feb. 6, 1934UNITED STATES PATENT OFFICE 2 Claims.

The invention appertains in particular to a furnace equipped with a coalblower.

The aim of the invention is to produce an efficient and reliable igniterfor preventing explosions or what is commonly referred to as blowbacksin the furnace due to accumulated gases suddenly becoming ignited.

The invention attains its object by the provision of an electric systemfor producing an arc over and above the coal bed to ignite gases risingtherefrom and in the adoption of an element designed to act inconjunction with the arc to catch gases to ensure their combustion.

The device comprises in the main an inverted chambered element in whichgases'are caught and their combustion assured by an are from electrodessurrounded by a support extending through the wall of the charging doorof the furnace.

A guard is preferably employed to protect the electrode points againstinjury, while the aforesaid support by loosely surrounding the electrodes provides an air space that heat insulates them.

Referring to the accompanying drawing, Figure 1 is a vertical sectionalview of the device applied to a furnace.

Figure 2 is a plan view of the underside of the device showing it partlyin section.

Figure 3 is a cross section taken on the line 3-3 of Figure 2.

Figure 4 is a further cross section but taken on the line 4-4 of Figure2.

Like numerals of reference indicate corresponding parts in each of thefigures throughout the drawing of the invention.

In the drawing in which the preferred construction is illustrated, theusual feed or charging door of the furnace is denoted at 5 and the firebed is represented at 6. It is desirable to mount the device upon thefeed door in order that it may swing clear of the combustion chamberwhen replenishing the coal. To this end the door is provided with anopening through which the support or casing 7 projects into thecombustion chamber. The inner end 8 of the support carries a head 9 inthe form of an inverted cup-shaped member adapted to catch gases risingfrom the fire bed 7. The vertical wall 9 has horizontal openings throughwhich electrodes 10 and 11 are inserted. The points 13 are bent towardseach other and are spaced to provide a gap for producing the arc. Thepoints are disposed well within the head which composes a canopy forthem. To shield the points against injury the canopy may have a guardconsisting of straps as at 14 extending from one side to the other ofthe head and preferably constructed integrally therewith. The head maybe of a cast iron member detachably secured to the support by fasteningelements. This is achieved by bolts and nuts 15 securing the lugs 16.

The electrodes are held in place by the provision of shoulders in theporcelains 17 which are engaged by threaded bushings 18. The electrodesare of a length sufficient to extend through and beyond the outer end ofthe casing so that the terminals 19 may be attached to the leads fromthe electric circuit. These parts may be housed by the cover 20 of thetransformer, not shown since it does not form a part of the presentinvention.

It is preferred to bolt the support to the door. To this end lugs 21 arefurnished on the sides of the support to take the bolts 22. Spacers 23of different lengths may be used to vary the distance at which the headis located in the combustion chamber.

It will be manifest that according to this invention unconsumed gasesrising from the fire bed are caught in the canopy 9 and ignited by theare between the electrodes and in this man ner effectively preventexplosions of accumulated gases. The electrodes for almost their entirelength are heat insulated by the air space within the casing, whichcommunicates with the outside of the furnace. The arcing of course needonly take place while the blower is operating.

Whilst the invention is shown and described in what is deemed its mostpractical form, various changes may be resorted to without departingfrom the spirit and scope of the appended claims.

What I claim is:-

1. In a device of the class described, a head for disposition in thecombustion chamber of a furnace, electrodes projecting into the head andhaving spaced points for producing an arc, said head forming a canopyfor the electrodes and being adapted to catch gases, a guard for theunderside of the canopy, and a support for the head.

2. In a device of the class described, a head for disposition in thecombustion chamber of a furnace, electrodes projecting into the head andhaving spaced points for producing an arc, said head forming a canopyfor the electrodes and being adapted to catch gases, straps extendingacross the underside of the canopy to form a guard for the electrodes,and a support for the head.

ALFRED SHEARMAN.

